x = linspace(-1,1);
% 原函数
plot(x,1./(1+25*x.^2),'k');
hold on;

% n = 5
plot(x,0.575823 + 0.350201*x.^1 + -2.04013*x.^2 + -0.271473*x.^3 + 1.5815*x.^4, 'r');
hold on;

% n = 10
plot(x,1 + 9.83798e-07*x.^1 + -6.58386*x.^2 + -8.22385e-06*x.^3 + 17.2673*x.^4 
+ 2.38141e-05*x.^5 + -19.1599*x.^6 + -2.7769e-05*x.^7 + 7.54325*x.^8 + 1.12362e-05*x.^9, 'g');
hold on;

% n = 15
plot(x,0.989741 + -0.349949*x.^1 + -17.1859*x.^2 + 3.00343*x.^3 + 147.498*x.^4 
+ -13.0367*x.^5 + -640.228*x.^6 + 30.4444*x.^7 + 1495.11*x.^8 + -38.84*x.^9 
+ -1907.41*x.^10 + 25.4828*x.^11 + 1251.44*x.^12 + -6.72371*x.^13 + -330.196*x.^14, 'b');
hold on;

% n = 20
plot(x,0.927543 + 3.24001e-07*x.^1 + -15.9429*x.^2 + -2.42078e-05*x.^3 + 159.464*x.^4 
+ 0.0005758*x.^5 + -926.019*x.^6 + -0.00594106*x.^7 + 3256.62*x.^8 + 0.0319824*x.^9 
+ -7144.95*x.^10 + -0.0979234*x.^11 + 9826.24*x.^12 + 0.176486*x.^13 + -8225.83*x.^14 
+ -0.185038*x.^15 + 3829.31*x.^16 + 0.104277*x.^17 + -759.786*x.^18 + -0.0243965*x.^19, 'y');
